Lightly spray a baking sheet with olive oil cooking spray. Arrange the zucchini slices in a single layer on the baking sheet. Spray them lightly with olive oil cooking spray. Broil (or grill) the zucchini for about eight minutes or until tender and very lightly browned. Set aside to cool.

To prepare the meat sauce, cook the sausage in a nonstick skillet over medium-high heat for about three minutes, stirring occasionally with a wooden spoon to break up any clumps. Add the bell pepper, onion, and garlic, and cook for about four minutes longer, until the meat is no longer pink. The juices should be cooked dry. Stir in the marinara sauce and bring to a boil. Reduce the heat and simmer for about five minutes, stirring frequently. The sauce will be very thick.

Meanwhile, in a mixing bowl, combine the egg whites, ricotta, Italian seasoning and black pepper until well combined.

To assemble the lasagna, spread half of the meat sauce in the bottom of the prepared baking pan. Layer on half of the zucchini slices, followed by half of the ricotta mixture and half of the mozzarella cheese. Repeat with the remaining meat sauce, zucchini slices, ricotta mixture, and mozzarella. Sprinkle with parmesan cheese. Bake for about 40 minutes or until bubbly and lightly browned. Let stand for 5 minutes before serving.